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One credential in a city employee's wallet, two things crossing the border: licensed data flows from Flanders to Germany, and a German entitlement is recognised in Flanders. This page shows the architecture behind the recording, block by block, and what it means for a city that wants to join.
Two planes, built on open standards. On the data plane, the DECIDE Dataspace App discovers a licensed dataset in the Flemish DCAT catalogue and retrieves it through a data space connector. On the identity plane, a Verifiable Credential proves that the person is entitled to do so, once against our own purchase gate and once at the Flemish login.
Architecture. Left: Germany, built and operated by [ui!]. Right: Flanders, the lblod platform operated by ABB / Digitaal Vlaanderen with data from the City of Ghent. The wallet sits outside both, because it belongs to the person: a standard smartphone app from the App Store or Google Play. Solid arrows are live calls, the green one is the cross-border retrieval; dashed arrows describe or establish trust.
One value links both planes. The licence level in the credential
(bought) is the same value the connector sends as the
dsp-role header when it fetches data. The identity plane proves that
the person holds the level; the data plane uses the level to retrieve the data.
The retrieval is not just technically possible, it is demonstrably legitimate.
Six steps from credential to cross-border retrieval. The first happens once; everything else a city employee can repeat as often as needed. The recorded walkthrough shows the same systems live.
An employee of a pilot city signs in at the DECIDE Credential Issuer and
scans a QR code with the wallet on her phone. The wallet fetches the
credential via OID4VCI and stores it as a card. It states her organisation
and her licence level, signed under the issuer's did:web
identity.
In the Dataspace App she opens the catalogue and filters for licensed offerings. The Flemish "Licensed Dataset" shows its licence, attribution and access conditions, exactly as the Flemish DCAT catalogue describes it.
"Buy licence" opens a QR code instead of a form. The wallet presents the
credential via OID4VP; the entitlement verifier checks issuer, signature
and licence level before the subscription is created. A credential with
the level viewer is refused, with the reason stated.
The data space connector queries the licence-gated Flemish endpoint with the provider's access key and the licence level. It receives the datasets Flanders releases for that level, such as the Restricted Mobility Zones and ELI legal metadata, and logs every retrieval with timestamp, status and record count. In production since July 2026.
The map view draws GeoJSON zones straight from a retrieved payload, and the search filters retrieved records by keyword with a live match count. Both views are generic: whatever the connector delivers, they display.
At the Flemish data portal she chooses "Scan QR code". The wallet presents
the same credential to the Flemish verifier, which resolves our
did:web, checks the signature against its trusted-issuers list
and answers accepted. A German entitlement, recognised in
Flanders, since July 2026.
What each box in the picture does, and who runs it.
The cities are the customers. Their staff discover datasets, acquire licences and retrieve data. Each city is a separate tenant with its own subscriptions and retrieval history.
Catalogue, licence purchase with QR code, subscriptions, retrieval history, map view and search. Fully bilingual, German and English, so city staff work in their own language.
Holds catalogue, subscriptions and retrieval history, checks entitlement on purchase and polls subscribed offerings automatically, hourly by default. Access keys live only on the server.
The component that crosses the border. It queries the licence-gated Flemish endpoint with access key and licence level and records every retrieval, so a city can prove when it fetched what.
The purchase gate. It requests the credential from the wallet via OID4VP and admits a purchase only if issuer, signature and licence level check out. No credential, no licence.
Issues Verifiable Credentials for the German pilot cities under
did:web:decide.ai-native-ri.eu, in the SD-JWT VC format, via
OID4VCI. Listed as a trusted issuer by the Flemish verifier.
Describes every Flemish dataset with title, access conditions and the endpoint through which it is reached. New datasets become visible to the connector as soon as they are described here.
The open query point for public datasets and the catalogue itself. Anyone can check here what Flanders publishes, with no credentials at all.
The protected query point. It answers only requests that carry a valid access key and a licence level, and returns only what that level is entitled to see.
The credential check behind the Flemish login. It resolves the issuer's
did:web, verifies the signature and consults a list of trusted
issuers, which includes the DECIDE Credential Issuer.
A standard smartphone wallet, in the pilot Paradym for iOS and Android. It holds the credential and presents it wherever entitlement is asked for: at the purchase gate and at the Flemish login.
Who is involved. ABB, the Agency for Home Affairs of the Flemish government, leads the project and operates the lblod platform; the City of Ghent supplies the data. [ui!] Urban Software Institute leads the use cases and represents Freiburg and Bamberg. The University of Applied Sciences Kehl and the University of Jena accompany the pilot as stakeholders.
No proprietary middleware. Every interface in the picture is an open standard, so the next city, and the next pilot, can build on the same contracts.
The interface contracts, the issuer profile and the wallet compatibility rules are documented in the shared project write-up, including the consortium's analysis of the Dataspace Protocol.
Two kinds. From Flanders, the connector retrieves the datasets the lblod platform releases for the city's licence level, described in DCAT: the Restricted Mobility Zones of use case 1, ELI legal metadata, decision annotations and more. Which datasets these are is decided in Flanders and can change at any time.
The catalogue also carries sample offerings from the open data portals of Freiburg and Bamberg, such as social areas or cycle paths, so that the complete workflow from discovery to map can be tried end to end. Their licence levels are illustrative; the Flemish entry is the live one.
Yes. The connector asks for everything Flanders describes for the city's licence level, so a newly described dataset appears in the next retrieval, at the latest with the next automatic poll. It does not become a separate catalogue entry with its own licence in the Dataspace App; discovery of individual datasets stays with the Flemish DCAT catalogue, by design.
Credentials, a catalogue entry and the documented contracts. No new middleware.
Interested? info@ui.city
The recorded walkthrough on this site, the open documentation of every interface in the shared project write-up, and the knowledge that a municipal pilot can share licensed data across a border with focused components and open standards, without heavyweight middleware. The demonstrator itself is available to project partners on request.
bought may purchase and retrieve, viewer may only look. The value that links identity and data.